Methanol continues to be a chemical of interest because of its importance as a common solvent and in various applications such as fuel cells and catalysis. Structurally and chemically, the existence of both a hydrogen-bond-forming hydrophilic group and a small hydrophobic methyl group leads to the molecule's rich behaviors, especially at interfaces. To distinguish the interfacial properties from the bulk ones, surface-sensitive or even specific methods are needed. Here, using reflection high-energy electron diffraction as a contactless, surface-specific technique for direct structure probing, the unique self-assembling behaviors of vapor-deposited methanol assemblies on hydrophobic surfaces were revealed for the first time. Hidden structural transformations were uncovered, which have been obscure in spectroscopic and other indirect measurements. Furthermore, thin methanol ice forms 2- and 3-dimensional, long-range orderd structures at different temperatures, depending on the annealing procedures used. These findings may reconcile the inconsistent previous reports for the crystallization of interfacial methanol, whose process is in fact far beyond a presumed single-stage description.

Structural transformations and self-assembly of interfacial methanol ice on hydrophobic surfaces

253rd National Meeting (2017)

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